1. Technical Area of the Invention
The invention relates to an electrical ignition procedure for internal combustion engines, whereby an arrangement of multiple electric coils and a magnetic generator is used, which is coupled to the internal combustion engine by its crankshaft for example, and which turns synchronously with it. With this, the magnetic field of the magnetic ignition generator flows through the coils at times, and a sequence of magnetic flux alterations is generated for each revolution. By this means, corresponding alternating current half waves are induced in the coils.
In the invention-specific ignition system, the alternating current half waves are used for the following:                an energy storage element, for example an ignition capacitor, is charged with alternating current half waves and discharged via the primary coil winding of an ignition transmitter for triggering an ignition spark for the cylinder or other combustion space of the internal combustion engine.        the alternating current half waves are scanned, detected, processed and/or evaluated or filtered by a microelectronic and/or programmable control device. An output result of this processing consists in determining an ignition time in dependence on the detected and evaluated alternating current half waves and/or on some other state of the internal combustion machine, such as its rotational setting or speed. In correspondence to the ignition time determined by the control device, the ignition switch is activated for generating an ignition spark.        Additionally, alternating current half waves at least partially of the control device are forwarded to its voltage or current supply.        
2. State of the Art
The German patent disclosure texts DE 19 54 874, with an English equivalent in U.S. Pat. No. 3,703,889, and DE 24 19 776, with an English equivalent in U.S. Pat. No. 3,993,031, and U.S. 2002/0 117 148 A1, describe ignition systems that each have speed limitations but without using digital and/or programmable control electronics. Alternating current half waves generated in the coils are used directly for controlling the ignition switch or to trigger the speed limitation. According to DE 24 19 776, when a permissible maximum speed is exceeded, the switching thyristor is guided to discharge the ignition capacitor of a negative half wave, which directly precedes a positive charging half wave for the ignition capacitor. By this means, the charging half wave can flow out over the break of the ignition thyristor, whereby a charging of the ignition capacitor is prevented and the ignition now is stopped. After attenuation of the charging half wave, the switching thyristor again goes back into a locked state. If, through stoppage of the ignition, the speed (again) drops below the maximum value, then the switching thyristor no longer is controlled for a sufficient duration by the (preceding) negative voltage impulse of a control winding. It is then already in a locked state with the start of the (subsequent) positive charging half wave. The ignition capacitor is now again charged, and by the ignition time, an ignition is introduced with the following voltage impulse of a control voltage. In any case, guidance of the ignition thyristor in the speed limitation also takes place at times (DE 24 19 776, FIG. 2 positive Us signal) when it does not have to be guided to short-circuit the positive charging half waves. From this a purposeless consumption of current arises. Additionally, the layout according to this state of the art is not at all suited for a current-saving concept with a digital control device. The guiding signal Us for the ignition discharge switch of necessity derives from the physical layout. US 2002/0 117 148 A1 teaches that with an active speed limitation via a trigger capacitor, a time window expands for guiding the ignition switch to prevent charging of the ignition capacitor by charging half waves to the extent that with excess speeds, the ignition switch is guided for an entire revolution, with corresponding current consumption.
From U.S. 2003/0 089 336 A1, an ignition system is known with a programmable microcontroller as the control device, which scans induced alternating current half waves in the magnetic generator, processes them internally, and from that can make assessments of the state of the internal combustion engine, especially its rotation setting, speed and rotary acceleration. According to ignition strategies that can be programmed in, an ignition switch can be intelligently guided. To supply current to the microcontroller, a separate supply coil is provided in the magnetic generator. The coil output is connected with a power supply circuit for the microcontroller. This has a special output to guide the ignition switch for the purpose of discharging the ignition capacitor. The goal of the published technical teaching is a lengthening of the ignition spark combustion duration with the named pusher effect while simultaneously optimizing the energy content of the ignition spark. Particular modes of operation such as switching off, limiting speed, or stroke disruption are not addressed.
EP 1 643 120 A2 shows a process-controlled ignition system in which pins of the processor chip are directly connected with the input winding of the magnetic generator. The external current to the processor chip is not limited. It is otherwise according to EP 1 496 249 A1, according to which a current supply unit for an ignition control microcomputer does have a current limitation resistance in the area of 2 kΩ). In its current supply path, for voltage stabilization, a direct controller is inserted with multiple components for supplying the microcontroller with current. In EP 1 496 249 A1, FIG. 15 shows that the ignition switch is guided with the signal s4 over a full revolution of the rotor, so that after recognition of the “shutdown” state (h1 in FIG. 15, part c), even after the shutdown switch 10 has been released (see FIG. 12), charging of the ignition capacitor is prevented by short-circuiting the positive charging half waves, for which see FIG. 15, signal e1.
US 2006/0 191 518 A1 discloses an ignition system guided by a processor or microcontroller with a stop button function to initiate a shutdown process of the internal combustion engine. After this button is released, it is necessary to continue preventing generation of ignition sparks until the engine shuts down. For this, the charging current for the ignition capacitor from an alternating current half wave is short-circuited by the ignition switch, to prevent charging of the ignition capacitor.
The “speed limitation,” “stroke disruption” and “shutdown” operating modes are known. With each of these there is a reduction in speed, for which a spark shutoff is used fully or in part.
As is known per se, the “speed limitation” mode of an internal combustion engine (combustion motor) is initiated as soon as a certain motor speed is exceeded. For this the state of the art is to initiate a spark switchoff above the speed limitation, and thus on the spark plug, formation of an ignition spark is prevented. For this, the ignition switch is constantly guided above the speed limitation, to prevent a charging of the ignition capacitor, whereby the current from the charging coil is short-circuited to ground. The ignition switch is precluded from not being guided, since typically the combustion motor, in an instance where the load is slightly lessened, is accelerated over the limit speed so that it remains above this threshold for multiple revolutions, and thus the ignition capacitor would be charged up to a multiple of its permissible voltage. By means of voltage limitation components such as a varistor, this in fact would be prevented, but the component expense, and thus manufacturing cost, is increased.
in U.S. 2002/0 11 71 48 A1, as well as in the above EP 1 469 249, constant guidance of the ignition switch to switch off ignition sparks is depicted, for which see FIG. 11 in EP 1 496 249, with the signal s4 there depicting the guidance of the ignition switch. It is evident that when the speed is exceeded during a complete motor revolution, the ignition switch is guided, independent of what amplitude and polarity the induced voltage in the charging coil 6 (FIG. 2 in EP 1 496 249) has. The ignition switch itself is also guided if the ignition capacitor would not be charged by the charging coil, the disadvantage being that current is consumed unnecessarily.
From the state of the art indicated above, it is clear that a part of the energy derived from the flux changes in the magnetic generator is used to supply the control electronics. This need to be supplied is composed decisively of the current consumption for a microelectronic control device and the guidance of the ignition switch. With modern microprocessors, the current consumption of the microelectronic control device can be much reduced, values under 1 milliampere can easily be met. By this means, the share of the guidance current for the ignition switch attains ever greater significance in the overall current supply. For the most part, the guidance current for the ignition switch is at several milliamperes, which is also caused by the fact that according to circuit technology, a resistance is always switched parallel to the control input of the ignition switch to ground. By this means, insensitivity to disturbing effects, and especially protection against being switched on erroneously is achieved.
It can be said by way of summary from the state of the art that with activated ignition switches, the current consumption determines the layout of the control device's power supply. A preset amount of energy is drawn from the charging coil into the control device's power supply, therefore the coupling between the charging coil and the power supply can be designed to be preset in how high the ohmage is.
One task of the invention is to ensure the ignition switch will be guided most of all during shutoff operations, even when, owing to the ignition module being wrongly installed in service, the air gap between the rotating magnet wheel and the rewound yoke core deviated from the 0.3 mm at most that is nominal to 2 mm, for example.
An additional task of the invention consists in being able to use structural components for the ignition system that have increased mechanical tolerances and thus lower costs. For example, the installation play in the attachment boreholes of the yoke care should permit setting of a relatively large air gap when parts are unfavorably paired. When the air gap is large, the voltage falls, which is induced in the charging coil surrounding the yoke core, and therefore a further task of the invention is to be able, by means of circuit-technical dimensioning within the ignition system, to divert enough current from a charging coil surrounding the yoke core, despite increased mechanical tolerances, to supply the control device with power.
To fulfill certain relationships and boundary conditions of various motor types, the “stroke disruption” operating mode is known, in which, similar to with the speed limitation, an ignition spark shutoff or suspension is used as a combustion shutoff, multiple times according to a certain pattern. In particular, the “stroke disruption” operating mode is used at relatively low speeds, such as idling. With this, a problem arises in that for discharging of the ignition capacitor, the ignition switch must be given more lengthy guidance, since with the relatively low speed, the period duration of a revolution is longer. Thus the task of the invention is to be able to ensure energy removal for the ignition switch control device at low speeds, down to idling.